Flying-machine propeller



Nov. 16 1926.

w. STIEBER FLYING MACHINE PROPELLER Filed May 5, 1921 FIG/1. F1625. Fl 6.3.

, INVENTOR: v

Patented Nov. 16, 1926.

. UNITED STATES PATENT, OFF-ICE.

WILHELM STIEBER, OF AMBER G, GERMANY, ASSIGNOR'TO THE FIRM: RUPPEL BROS. 4

' METALLWARENFABRIK, OF GOTHA, GERLIANY.

FLYING-MACHINE PROPELLER.

Application filed an 5, 1921;8eria1 No.

My invention refers to metallic propellers for aerial vehicles and more especially flying machines and its particular object is to pro vide a metal propeller of superior resistivity against the action of centrifugal force.

In order to combine lowest possible weight, highest security of working and greatest efliciency, the blades of the propeller according to the present invention are 10 formed of an suitable number of superposed metal p ates, these said plates being ,cut out in the places, where they overlap one another, in such wise that each blade forms a body of substantially uniform strength throughout.

The propeller thus forms a hollow body composed of two cup-shaped parts conslsting of sheet metal, the one part formmgthe pressure side, the other one the suctlon side.

The pressure side, instead of being formed of a single plate, is composed of aplurahty of plates placedfstepwise one upon the other, the number of plates increasing in the d1- rection towards the axis in proportion to the increasing strain. Instead of being cut olf straight, the single plates areprovided with indentures of substantially triangular form, such indentures providing that a uniform load is placed on the plates throughout the length of the-blade.

In the drawings affixed to this specification and forming part thereof a propeller embodying my invention is illustrated by way of example in a purely diagrammatic manner.

In the drawings Fig. 1 is a front view, and

Fig; 2 a side elevation of one blade, while Fig. 3 is a longitudinal section on the line II in Fig. 1.

Referring to the drawings, each blade has the form of a hollow sheet metal body. According to my invention that part of the blade which forms the suction side, when 466,973, and in Germany October 1, 1918.

the propeller is running, is made of a Single metal plate. In contradistinction thereto that portion which acts as pressure side, is formed of a plurality of metal plates, three such plateso, b, a being provided in the case disclosed in the drawings, these plates -being superposed and interconnected so as to formnear the basis of the blade a reinforced portion oftriple strength. The plates 0, b, and a differ in length, plate 0 extending from the blade basis only over about onevfourth of the entire length of the blade and a forming the innermost layer, whereas the middle plate 6 extends over about three-fifths of the entire lengthfonly the outermost plate a having vfull length. Obviously this arrangement of plates of different length corresponds to the different strains exerted by the centrifugal forces upon the different portions of the blade. In order to still more efiectively relieve the blade, the two shorter blades 0 and b are cut out from their ends down to about half their length, narrow triangular indentures e and f being formed in the blades 0 and b, respectively, whereby the stresses acting on the plates in different parts of their length are nearly equalized.

Obviously m invention is by no means restricted to-a blade composed of three superposed platesof different length nor to any-particular form of indenture.

I claim e A hollow sheet metal aircraft propeller comprising hollow blades, a portion of each blade being formed of a plurality of superposed metal plates of diiierent length rigidly connected with one anot er and cut out triangularly so as to equalize the centrifugal stresses exerted on-difi'erent portions of each propeller blade.

In testimony whereof I aflix my signature. 

